Half to peeet b



(No Model.)

H. F. LEARNARD.

' BLASTING PLUG.

Patented Oct. 19, 1886.

HcberFLem ward.

Attorney I NiT Eb STATES PATENT OFFICE.

HEBER F. LEARNARD, OF FORT COLLINS, COLORADO, ASSIG-NOR OF ONE HALF TO PERRY B. LEARNAB-D, OF SAME PLACE.

BLASTING=PLUG.

SPECIFICATION forming part of Letters Patent No. 351,273, dated October 19, 1886.

To aZZ whom it may concern: I

Be it known that I, HEBER F. LEARNARD, a citizen of the United States of America, residing at Fort Collins, in the county of Larimer and State of Colorado, have invented certain new and useful Improvementsin Plugs for Blasting; and I do hereby declare the following to be afull, clear, and exact description of the inventi0n,such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the ac companying drawings, and toletters or figures of reference marked thereon,which form a part of this specification.

My invention relates to certain new and useful improvements in plugs for drill-holes, the object of my invention being to provide a means whereby an air-chamber can be formed at the base of the drill-hole, which will render the blast more effective.

In the accompanying drawings, which illustrate my invention, Figure 1 is a perspective View of a plug constructed in accordance with my invention, and Fig. 2. is a sectional view showing the same applied to a drill-hole.

A refers to the stem of the plug, which is preferably made of wood. To one end of the same is attached a washer, B, which is com posed of some elastic or flexible material, said Washer being attached to the stem in any suit able manner, as by a small nail or screw.

C refers to a washer or plug, which is of larger diameter and thickness than the washer B, said portion 0 being secured to the stem in any suitable manner. In practice I have found hard rubber to answer well for the end washers.

The plug, when it is'desired to use the same, is driven to the lower end of the drill-hole, so as to compress the air therein, thelower washer, B, serving as a guide, while the upper washer, C, completely fills the drill-hole, so

(No model.)

that the cannot pass between the sides thereof. WVhen the plug has been placed in position the charge is placed above the washer 5 C, and it is tamped in the usual manner.

I have in practice demonstrated that by the use of the plug hereinbefore described onehalf the quantity of powder when used with the plug, as hereinbefore described, is as effeetive as double the quantity used in the old way. When this device is inserted in the drillhole, it will clear the same of any dirt and provide a dry surface, upon which the powder may rest.

The device hereinbefore described acts very much on the same principle as an air-cushion abovea charge of powder in fire-arms, it being well known that such an air-space will burst the gun with but asmall charge of powder.

I am aware that it has been proposed to provide a plug for'drill-holcs for the purpose of blasting roeks,as shown in Patent No. 49,925, granted to G. C. Bunsen, and I therefore do not claim, broadly, any device for forming in 55 a drill-hole an air-cushion; but

\Vhat I claim as new, and desire to secure by Letters Patent, is-

The improved plug for blasting purposes, adapted to be inserted in the lower or bottom portion of a drill-hole, said plug consisting of an imperforate washer, B, of elastic or flexible material, attached to the lower end of a stem, A, said stem having attached to its upper end a larger imperforate washer, C, said washer being of such a size as to completely fill the drill-hole and form an air-cushion beneath the charge, substantially as shown.

In testimony whereof I affix my signature in presence of two witnesses. 

